PALMER DEEP (SITES 1098 AND 1099)

The 192-nmi transit to Site 1098 (scientific prospectus site APSHE-13A) was accomplished at an average speed of 10.5 kt. During the voyage, 52 icebergs were seen on the 24 nmi range of the radar, and the vessel was required to alter course to avoid one large berg. Once in the Palmer Deep area, we ran a short 3.5-kHz PDR survey from south to north over the site. Drilling operations began at 1530 hr on 12 March with the deployment of a beacon.

During operations at this site, Eugene Domack joined the vessel for less than a day from the Laurence M. Gould (LMG) to observe procedures. Domack was the lead proponent on the proposal for drilling the Palmer Deep sites. Shortly before the LMG arrived, the Polar Duke came alongside Crane 3 to offload a logging tool and acetone, which had been shipped to Punta Arenas but had failed to arrive at the port call in time. These supplies had been delivered to the American base at Palmer Station a few miles away by the LMG for pickup by the Polar Duke.Site 1098
The initial core of Hole 1098A recovered 1.9 m, establishing seafloor depth at 1012 m (1022.6 mbrf). APC coring then continued through Core 7H, where contact with glacial till or hard basement concluded the hole exploration at 45.9 mbsf. Calm conditions permitted very good core recovery. The drill string was raised above the seafloor to begin Hole 1098B, and the ship was offset 10 m north.

To achieve stratigraphic overlap, Hole 1098B was spudded with the pipe 3.5 m lower than for the first core of Hole 1098A. Core recovery indicated a seafloor depth about 1.4 m shallower than at Hole 1098A. APC coring advanced to 43.0 mbsf (Core 5H). Adara tool heat-flow measurements were obtained with Cores 4H (34.5 mbsf) and 5H (43.0 mbsf). The drill string was raised above the seafloor at 0355 hr to begin Hole 1098C, and the vessel was offset 10 m north.

The pipe was set 3 m lower than at Hole 1098B for the first APC core at Hole 1098C. Coring began at 0430 hr 13 March with an Adara tool deployment just above the bottom before spudding on the first core. Five APC cores were collected, and coring operations ended at 0630 hr. Core recovery for the site averaged 101.6%. The drill string was recovered, the beacon successfully retrieved, and the vessel was under way at 0930 hr 13 March for a 6-nmi transit to Site 1099.

Site 1099
Site 1099 (scientific prospectus site APSHE-15A) was located using GPS coordinates, and a beacon was launched at 1030 hr 13 March. APC coring at Hole 1099A began at 1445 hr on 13 March with a 5.3-m core that established the seafloor depth at 1399.9 m (1411.2 mbrf). Continuous cores were taken to 62.3 mbsf (102% recovery) with Adara tool heat-flow measurements at Cores 5H (43.3 mbsf) and 7H (62.3 mbsf). An additional Adara tool was deployed with the initial core barrel before spudding the hole to measure the near-bottom-water temperature. A change of wind then moved several icebergs toward the vessel. The bit was pulled above the seafloor at 1900 hr, and the vessel was offset away from the icebergs.

At 2145 hr, after the icebergs had moved past, Hole 1099B was spudded and the bit washed down to 60 mbsf where APC coring resumed. Core recovery averaged 102% while advancing to 107.5 mbsf, which was considered the depth objective for the hole. The drill string was retrieved and the beacon recovered before the vessel's departure at 0445 hr on 14 March.